1. Technical Field
The present disclosure relates to a method of indicating scheduling assignment in device to device wireless communication, and D2D-enabled wireless device using the method.
2. Description of the Related Art
Device to device communication (D2D) is direct communication between devices and such kind of communication could happen within network coverage (for commercial case) and without network coverage (public safety).
In the device to device communication, the communication system comprises multiple D2D-enabled wireless devices communicating via successive scheduling assignment (SA) periods, and each of SA periods includes a SA pool and a data pool. The SA pool of the SA period is used for transmitting SAs for assigning data resources of the data pool of the SA periods for the same or different D2D-enabled wireless devices.
FIG. 1 shows a diagram that a SA pool of a SA period is used for transmitting SA for assigning data resource of the data pools of multiple successive SA periods for the same D2D-enabled wireless device. In FIG. 1, for example five SA periods including SA period #1, SA period #2, SA period #3, SA period #4, and SA period #5 are shown, each of the SA periods includes a SA pool as indicated by reference numerals 101, 102, 103, 104, 105, a data pool as indicated by reference numerals 111, 112, 113, 114, 115.
As shown in FIG. 1, the SA pool 101 of the SA period #1 is used for transmitting SA for assigning the data resource of the data pools 111, 112, 113, 114, 115 of the SA period #1, SA period #2, SA period #3, SA period #4, and SA period #5, and the SA pools of the SA period #2, SA period #3, SA period #4, and SA period #5 are not used for transmitting SAs any more. In the SA pools which do not transmit SA, the UE can receive SAs transmitted by other UEs. In this situation, the D2D-enabled wireless device does not need to transmit SAs in each SA period, and it can improve the ratio of receiving SAs, and save the transmission power of the D2D-enabled wireless device.
However, since the source allocation is based on D2D-enabled wireless device's own selection, the SA and/or data transmissions may collide if the D2D-enabled wireless device misses assignment signaling, which is for example transmitted in SA period #1 to indicate data resources in all five SA periods in FIG. 1.